Merge pull request #93 from blehnen/fix/preload-plugin-assemblies

fix: preload plugin assemblies at startup for type resolution

Author: blehnen

Source/DotNetWorkQueue.Dashboard.Api.Tests/Extensions/DashboardExtensionsTests.cs

@@ -1,8 +1,11 @@
 using System;
+using System.IO;
 using System.Linq;
+using System.Reflection;
 using DotNetWorkQueue.Dashboard.Api;
 using DotNetWorkQueue.Dashboard.Api.Configuration;
 using DotNetWorkQueue.Dashboard.Api.Services;
+using FluentAssertions;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -153,5 +156,85 @@ public void AddDotNetWorkQueueDashboard_Does_Not_Register_ConsumerPruningService
             Assert.AreEqual(0, pruningServiceRegistrations.Count,
                 "ConsumerPruningService should not be registered when tracking is disabled");
         }
+
+        [TestMethod]
+        public void AddDotNetWorkQueueDashboard_PreloadsAssemblies_From_AssemblyPaths()
+        {
+            // Copy a known DLL to a temp "plugin" directory
+            var pluginDir = Path.Combine(Path.GetTempPath(), "dnwq-preload-test-" + Guid.NewGuid().ToString("N"));
+            Directory.CreateDirectory(pluginDir);
+            try
+            {
+                // Use Newtonsoft.Json as a test DLL — it's in our bin but let's verify
+                // the preload path works by copying it and checking it loads from there
+                var sourceDll = Path.Combine(AppContext.BaseDirectory, "FluentAssertions.dll");
+                var destDll = Path.Combine(pluginDir, "FluentAssertions.dll");
+                File.Copy(sourceDll, destDll);
+
+                var services = new ServiceCollection();
+                services.AddLogging();
+
+                services.AddDotNetWorkQueueDashboard(options =>
+                {
+                    options.EnableSwagger = false;
+                    options.AssemblyPaths = new[] { pluginDir };
+                });
+
+                // If PreloadAssemblies threw, we wouldn't get here
+                var provider = services.BuildServiceProvider();
+                var opts = provider.GetRequiredService<DashboardOptions>();
+                opts.AssemblyPaths.Should().ContainSingle().Which.Should().Be(pluginDir);
+            }
+            finally
+            {
+                Directory.Delete(pluginDir, true);
+            }
+        }
+
+        [TestMethod]
+        public void AddDotNetWorkQueueDashboard_PreloadAssemblies_Ignores_NonexistentDir()
+        {
+            var services = new ServiceCollection();
+            services.AddLogging();
+
+            // Should not throw even if the directory doesn't exist
+            services.AddDotNetWorkQueueDashboard(options =>
+            {
+                options.EnableSwagger = false;
+                options.AssemblyPaths = new[] { "/nonexistent/path/that/does/not/exist" };
+            });
+
+            var provider = services.BuildServiceProvider();
+            provider.GetRequiredService<DashboardOptions>().Should().NotBeNull();
+        }
+
+        [TestMethod]
+        public void AddDotNetWorkQueueDashboard_PreloadAssemblies_Ignores_InvalidDlls()
+        {
+            var pluginDir = Path.Combine(Path.GetTempPath(), "dnwq-preload-invalid-" + Guid.NewGuid().ToString("N"));
+            Directory.CreateDirectory(pluginDir);
+            try
+            {
+                // Write a non-.NET file with .dll extension
+                File.WriteAllText(Path.Combine(pluginDir, "NotADotNet.dll"), "this is not a valid dll");
+
+                var services = new ServiceCollection();
+                services.AddLogging();
+
+                // Should not throw on invalid DLLs
+                services.AddDotNetWorkQueueDashboard(options =>
+                {
+                    options.EnableSwagger = false;
+                    options.AssemblyPaths = new[] { pluginDir };
+                });
+
+                var provider = services.BuildServiceProvider();
+                provider.GetRequiredService<DashboardOptions>().Should().NotBeNull();
+            }
+            finally
+            {
+                Directory.Delete(pluginDir, true);
+            }
+        }
     }
 }

Source/DotNetWorkQueue.Dashboard.Api/DashboardExtensions.cs

@@ -17,6 +17,7 @@
 //Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 // ---------------------------------------------------------------------
 using System;
+using System.IO;
 using System.Linq;
 using DotNetWorkQueue.Dashboard.Api.Configuration;
 using DotNetWorkQueue.Dashboard.Api.Controllers;
@@ -56,6 +57,10 @@ public static IServiceCollection AddDotNetWorkQueueDashboard(
             var options = new DashboardOptions();
             configureOptions(options);
 
+            // Pre-load user assemblies so Newtonsoft's TypeNameHandling binder can resolve
+            // message types during deserialization (before ResolveMessageBodyType runs).
+            PreloadAssemblies(options.AssemblyPaths);
+
             services.AddSingleton(options);
             services.AddSingleton<IDashboardApi>(sp =>
             {
@@ -258,6 +263,30 @@ private static void AddConnectionByTransport(DashboardOptions options, string tr
                     throw new ArgumentException($"Unknown transport type: '{transport}'. Valid values: SqlServer, PostgreSql, SQLite, LiteDb, Redis.");
             }
         }
+
+        private static void PreloadAssemblies(string[] paths)
+        {
+            if (paths == null || paths.Length == 0)
+                return;
+
+            foreach (var dir in paths)
+            {
+                if (!Directory.Exists(dir))
+                    continue;
+
+                foreach (var dll in Directory.GetFiles(dir, "*.dll"))
+                {
+                    try
+                    {
+                        System.Reflection.Assembly.LoadFrom(dll);
+                    }
+                    catch
+                    {
+                        // Not a valid .NET assembly — skip silently
+                    }
+                }
+            }
+        }
     }
 
     /// <summary>

Source/DotNetWorkQueue.Dashboard.Api/Services/DashboardService.cs

@@ -471,10 +471,15 @@ private static object SanitizeHeaderValue(object value)
         /// </summary>
         private Type ResolveMessageBodyType(string portableName)
         {
+            _logger.LogDebug("Resolving message body type: {PortableName}", portableName);
+
             // Stage 1: already loaded in AppDomain
             var type = Type.GetType(portableName);
             if (type != null)
+            {
+                _logger.LogDebug("Type resolved from AppDomain: {Type}", type.FullName);
                 return type;
+            }
 
             // portableName format: "TypeFullName, AssemblySimpleName"
             var commaIndex = portableName.IndexOf(',');
@@ -486,18 +491,30 @@ private Type ResolveMessageBodyType(string portableName)
             var dllFileName = assemblySimpleName + ".dll";
 
             // Stage 2: try loading from bin folder
-            var resolved = TryLoadType(Path.Combine(AppContext.BaseDirectory, dllFileName), typeFullName);
+            var binPath = Path.Combine(AppContext.BaseDirectory, dllFileName);
+            var resolved = TryLoadType(binPath, typeFullName);
             if (resolved != null)
+            {
+                _logger.LogDebug("Type resolved from bin folder: {Path}", binPath);
                 return resolved;
+            }
+            _logger.LogDebug("Assembly not found in bin folder: {Path}", binPath);
 
             // Stage 3: try configured assembly paths
             foreach (var dir in _assemblyPaths)
             {
-                resolved = TryLoadType(Path.Combine(dir, dllFileName), typeFullName);
+                var pluginPath = Path.Combine(dir, dllFileName);
+                resolved = TryLoadType(pluginPath, typeFullName);
                 if (resolved != null)
+                {
+                    _logger.LogDebug("Type resolved from plugin path: {Path}", pluginPath);
                     return resolved;
+                }
+                _logger.LogDebug("Assembly not found in plugin path: {Path}", pluginPath);
             }
 
+            _logger.LogWarning("Could not resolve type {PortableName}. Searched: bin={BinDir}, plugins=[{PluginDirs}]",
+                portableName, AppContext.BaseDirectory, string.Join(", ", _assemblyPaths));
             return null;
         }
 

docker/dashboard/DOCKERHUB.md

@@ -100,6 +100,30 @@ docker run -d \
 
 Set the connection string to the mounted path: `"Data Source=/data/sqlite/myqueue.db"`
 
+## User Message Assemblies (POCO DLLs)
+
+If your queues contain custom POCO types, the dashboard needs those assemblies to display typed message bodies. Mount a directory with your DLLs and configure the path:
+
+```bash
+docker run -d \
+  -p 8080:8080 \
+  -v "$(pwd)/appsettings.json:/app/appsettings.json:ro" \
+  -v "/path/to/your/dlls:/app/plugins:ro" \
+  blehnen74/dotnetworkqueue-dashboard:latest
+```
+
+Add to `appsettings.json`:
+
+```json
+{
+  "Dashboard": {
+    "AssemblyPaths": ["/app/plugins"]
+  }
+}
+```
+
+You can also build a derived image instead: `FROM blehnen74/dotnetworkqueue-dashboard:latest` and `COPY` your DLLs into `/app/plugins/`.
+
 ## Tags
 
 | Tag | Description |